1. Field of the Invention
The invention relates to driving devices for driving light source modules, and particularly to a driving device integrated with an AC/DC converter.
2. Description of Related Art
Conventionally, a liquid crystal display (LCD) panel uses discharge lamps, such as cold cathode fluorescent lamps (CCFLs), as light sources of a backlight system. Typically, an inverter converts a direct current (DC) signal output from an alternating current (AC)/DC converter to an AC signal to drive one or more light sources. The DC signal is normally from 5V to 24V.
Referring to FIG. 5, a block diagram of a conventional driving device is shown. The conventional driving device for driving a light source module 14 includes an AC power source 10, an AC/DC converter 11 and an inverter 12. The AC/DC converter 11 includes a power factor correction (PFC) circuit 110, a DC/AC converter circuit 111 and a transformer circuit 112. The inverter 12 includes a power stage circuit 120 and an inverter circuit 121.
The AC power source 10 outputs an AC signal that is transformed to a DC signal via the PFC circuit 110, and then the DC signal is converted to a square-wave signal via the DC/AC converter circuit 111. The square-wave signal is rectified and stepped down to another DC signal via the transformer circuit 112 and a peripheral rectify circuit in the transformer circuit 112. The inverter 12 converts the received DC signal to a sine-wave signal, and provides it to the light source module 14.
In the conventional driving device, the AC signal output from the AC power source is converted to the sine-wave signal via DC signal, square wave signal, DC signal and square wave signal, which has lower conversion efficiency, such as: about 70%. In addition, the conventional driving device has a higher cost, and occupied a larger area.